These are great responses and I agree with the reasons completely.
I'm also looking for things such as nickglover mentioned. That is, what changes could Disney make that would make you want to sell.
We know Disney will not breach the contract, but what "perks" or other implied benefits might they change that you would consider to be so important that you would want to sell if you lost them.
This is inspired somewhat by sgtpet's decision not to buy based on a perceived loss of flexibility, or at least the higher cost for that flexibility.
Personally, the kicker for me revolves around the implied promise that Disney made regarding the annual maintenance fees. If those really did rise 15% a few years in a row, it might make me upset enough to sell.
On the other hand, they can only raise the fees if the actual costs go up, which would have to be some pretty wild general inflation going on in the country, which would make the DVC deal seem even better.
So I guess I can't think of anything that would make me sell since the main reasons I bought are all contractually guaranteed!
Granny